The invention relates to a network user system and method of using the same, which can be used to connect one network user station to another network user station via a message line and to which, in a receive mode, a timer message including a time of day can be sent by a network user station as a means of improving time synchronization accuracy between network user stations.
Such a network user station is known from the Siemens catalog ST 70, chapter 12, 1997 edition. This network user station is suitable for use in a distributed automation system including a plurality of automation components, which must be synchronized for controlling a technical process in accordance with an automation task. To this end, a time transmitter connected to the network cyclically transmits a timer message via broadcasting or multicasting. The automation components use this transmitted timer message to synchronize their clocks. Due to different dwell times of a timer message in the transmitter of the network user station and/or in network components, the times contained in the timer message may be incorrect at the time when they are received.
German Utility Model Application 298 19 806.1 proposes to enable a network user station to correct the delay times between the instant when the time is entered into a time message and the instant when it is transmitted, and to correct the delay times between the instant when the time message is received and the instant when the time of day is further processed. This German Utility Model Application 29819806.1 corresponds to International Application PCT/DE99/03443 (published as WO 00/28400), which was filed in the United States as a Continuation Application (application number unknown) on May 7, 2001, and full disclosure of which is incorporated herein by reference.